CH 461 Lecture Notes - Lecture 24: Purine Metabolism, Nucleoside Triphosphate, Inosinic Acid
Document Summary
Nucleotides and nucleosides can be supplied to an organism by either a salvage reaction or by synthesis from smaller precursors. Salvage reactions convert free purine and pyrimidine bases into nucleotides. Additionally, free purines and pyrimidines can be degraded, the purines to the oxidized ring compound uric acid and the pyrimidines to smaller compounds ((cid:811) amino acids, not the (cid:810) amino acids found in proteins). Finally, purines and pyrimidines can be synthesized from smaller precursors ( de novo synthesis). Thus three interacting pathways for nucleotides, nucleosides, and the free bases exist: salvage, degradation, and biosynthesis. This complexity is due to the central role of nucleotides as energy currency, signaling molecules, and precursors to informational macromolecules in the cell. If the supply of nucleotides becomes limiting, cells couldn"t make dna or rna, for example. Likewise, cells need to have a balanced supply of nucleotides, because a and t, as well as c and.
